When I learned about Chernobyl reactor, I was surprised how bad the design decisions were. Casing the reactor core in wooden housing?
Re:The Nuclear Option
by i_am_proteus on Thursday February 14, 2019 @08:36PM
(#19167813)
IIRC the control rods were also bizarre and had graphite bottoms, so the first part of a trip (scram) was adding reactivity.
Prompt critical is prompt.
I believe the rods were graphite, just like the moderators. Of course the problem with that was that by the time they were inserted the reactor was already out of control. All the graphite rods did was burn, which certainly didn’t help matters! Worse, after a while the blocks of graphite used as the moderator also burned, and was difficult to extinguish. What they needed (other than better reactor design) was a ready store of neutron poisons that would have flooded the reactor vessel before rod insertion. Unfortunately, by the time they were using neutron poisons the explosion and fire had already destroyed anything like containment.
Chernobyl didn't have a containment or shield building. Manually disabling the safety systems didn't help.
The biggest problem with Chernobyl was the reactor design, which had a positive void coefficient, which outside of something like CANDU reactors is considered insane today. It’s true that their experiment with simulated blackout was the proximal cause, but the fact that increased steam production led to higher power output was the big factor that made it such a huge disaster.